mating systems

Question 1

monogamy

Answer 1

1 female, 1 male
mate guarding
mate assistance
female enforced

Question 2

polygyny

Answer 2

1 male, 1+ females
female defense
resource defense
scramble competition lek

Question 3

polyandry

Answer 3

1 female, 1+ males
resource defense
male defense

Question 4

2 main factors to consider?

Answer 4

male and female dispersion in space and time
-how easy is it to access mates?

patterns of desertion by either sex
- depends on cost and benefits of parental care

Question 5

Factors governing the diversity of mating systems

Answer 5

Mating systems WITHOUT male care

Mating systems WITH male care

Question 6

If males do not provide parental care

Answer 6

Assumption: male reprod. success limited by access to females

Prediction: males can compete for females directly or indirectly

Question 7

Low chance for Polygamy

Answer 7

Resources (food, nest sites) and/or mates are evenly distributed relative to defended territorie

Question 8

High chance for Polygamy

Answer 8

Patchy resource distributions enable some individuals to ‘grab more than their fair share’

Question 9

Operational Sex Ratio of 1:1

Answer 9

Ratio of reproductive males to reproductive females

If all females breed in synchrony and the real sex ratio is 1:1.

Question 10

common toad mating system

Answer 10

explosive breeders
– Breed only for a few nights
– Females synchronous
– More even (1:1) OSR
– Low variance in male success
– Resource defense not feasible
– Scramble competition

Question 11

bullfrog mating system

Answer 11

prolonged breeders
– Breed over extended period
– Females asynchronous
– Male biased OSR
– High variance in male success
– Resource defense feasible
– Resource defense polygyny

Question 12

Experimental evidence for Emlen and Oring (1977)

Answer 12

Female distributions governed by food
- In high food areas, female ranges are small and overlapping

Males follow to high female sites

Question 13

Mammalian mating systems depend on

Answer 13

resource and female dispersion patterns

Polygyny: females have smaller ranges than male territory

Monogamy: females have larger ranges than male territory

Question 14

leks and choruses

Answer 14

Agreggations of males on small mating territories

….each male displays for choosy females

mating is strongly skewed towards a few males

Question 15

lek paradox

Answer 15

Since females usually mate with one male,
why do other males bother to come to the lek at all?

And, if one male gets most matings, why is there still variance in male traits?

Question 16

lek paradox hypotheses

Answer 16

hotspot (Males settle on areas where
female encounter rate is high)

hot shot (Males cluster at leks to parasitize better signallers)

Males aggregate to reduce predation risks

Males aggregate to amplify signal and increase female attraction

Females prefer leks because they facilitate female choice

Question 17

Why are males monogamous?

Answer 17

Monogamous bird couples leave more descendents fi they share parental care
- familiarity improves parental performance
- older individuals have more experience

Monogamy exists because of low opportunities to be polygynous
- strong competition among males (hard to get 2nd mate)
- females likely suffer in polygyny because loss of help

Question 18

Female enforced monogamy hypothesis

Answer 18

Monogamy is not adaptive for males but forced into it

Male burying beetles

Question 19

why is social monogamy relatively rare in mammals but common in birds

Answer 19

Eggs develop internally in mammals, externally in birds

Differences in constraints and costs between sexes in parental care

Question 20

why does social monogamy not guarantee genetic monogamy

Answer 20

Extra pair copulations by both genders are common…
- males benefit: paternity
- females benefit: fertilisation success, genetic diversity, good genes

Question 21

DNA technology to assign parentage

Answer 21

microsatellites

Useful for assigning parentage and kinship because:
- highly polymorphic
- inherited in a Mendelian fashion

Question 22

polygyny threshold model

Answer 22

females may choose polygyny
costs of sharing a male’s help with parental care
outweighed by the benefits of gaining access to good resource

Question 23

what does polygyny threshold model assume

Answer 23

ideal free distributin

Question 24

3 broad themes in mating system diversity

Answer 24

Life history constraints
Ecological factors
Social conflicts